Grinding machine



Oct. 23, 1951 H. A. SILVEN 2,572,529

GRINDING MACHINE Filed July 17, 1948 10 Sheets-Sheet l HERBERT A. SILVEN Oct. 23, 1951 H. A. SILVEN 2,572,529

GRINDING- MACHINE Filed July 1'7, 1948 10 Sheets-Sheet 2 Inventor F Z v Heme/er H 5m vs/v a um Oct. 23, 1951 I H. A. SILVEN 2,572,529

GRINDING MACHINE Filed July 17, 1948 10 Sheets-Sheet 5 5mm I SIZ v E N 3/3 \JHEEL MOTOR =& la

' c MP mo. moron. I

F COO LANT M OTOR- NH EEL FEED CONTROL LEV ER WH.SLIDE REAR. TIMER. MANUAL L an azo WORK O Im en tor Fi 3 HERBERT 14.6mm

Httor'ncy 0a. 23, 1951 H, A, SILVEN 2,572,529

GRINDING MACHINE Filed July 17, 1948 10 Sheets-Sheet 4 Fi].4- I

lnven tor HERBERTHSILVEIY Httorney Oct. 23, 1951 H. A. SILVEN 2,572,529

GRINDING MACHINE Filed July 17, 1948 10 Sheets$heet 5 Inventor F 9-5 HERBERT/C). ILVEN ,Qttorney Oct. 23, 1951 H. A. SILVEN 2,572,529

GRINDING MACHINE 28 Q 6 E Invenrok Q Q 3 p2 HERBERTIQ.5ILVEN m a q q Hrrozna Y 23, 1951 H. A. SlLVEN 2, 7

GRINDING MACHINE Filed July 17, 1948 10 Sheets-Sheet 7 I/// Q N ZO'R liOa.

[1v VENTOR N HERBERT/q. SILVEN g w ikm Hrroezysy Oct. 23, 1951 H. A. SILVEN GRINDING MACHINE Filed July 17, 1948 10 Sheets-Sheet s 38; I Ft 9 INVENTOR HERBERT/q. SILVEN By Mum Hrrp/a nay Oct. 23, 1951 H. A. SILVEN 2,572,529

GRINDING MACHINE Filed July 17, 1948 10 Sheets-Sheet 9 Fi I3 [war/r012 HERBERT/QgS/LVEN Firrozmzy Oct. 23, 1951 H. A. SILVEN 2,572,529

GRINDING MACHINE Filed July 17, 1948 10 SheetsSheet 1O 7E lE- IIIIIIA INVENTOR HERBERT/QSILVE/Y B Win-3%- Hrromey Patented Oct. 23, 1951 GRINDING MACHINE Herbert A. Silven, Worcester, Mass assignor to Norton Company, Worcester, Mass., a corporation of Massachusetts Application July 17, 1948, Serial No. 39,362

33 Claims.

The invention relates to grinding machines and more particularly to a hydraulically operated cylindrical type grinding machine.

One object of the invention is to provide a simple and thoroughly practical cylindrical grinding machine. Another object of the invention is to provide an improved hydraulically operated table reciprocating mechanism. Another object of the invention is to provide a hydraulic table reversing mechanism for precisely controlling the reversal of the-table movement. Another object is to provide an independent dwell control for producing an adjustable dwell at either or both ends of the table stroke. A further object is to provide a reverse control valve which is arranged to gradually decelerate and accelerate the table movement prior to and after reversal.

Another object is to provide an improved hydraulically operated wheel feeding mechanism whereby a rapid approaching movement is imparted to the grinding wheel after which the grinding wheel is fed at a slower controlled rate during the grinding operation. Another object is to provide a wheel feed mechanism which is arranged to produce a rapid approaching movement of the grinding wheel, then a slower feed for a shoulder grinding operation after which the feed is further reduced to a slower predetermined body feed.

Another object is to provide a wheel feeding mechanism including a piston and cylinder to move the feed screw axially to produce a rapid approaching movement of the grinding wheel and a fluid motor thereafter to rotate the feed screw so as to impart a slow grinding feed to the grinding wheel.

Another object is to provide an improved hydraulic control mechanism whereby the grinding wheel may be fed continuously during a plunge-cut grinding operation or may be fed intermittently at the ends of the reciprocatory stroke of the table during a traverse grinding operation. A further object is to provide a selector valve to facilitate setting up themachine for either a plunge-cut or a traverse grinding operation.

Another object is to provide an automatically actuated mechanism to start the work drive and coolant pump motors when either a plunge-cut or a traverse grinding feed is initiated. Another object is to provide a hydraulically-actuated electrically-controlled mechanism automatically to start both the work drive and the coolant pump motors when either a plunge-cut feeding mechanism;

or a traverse grinding feed is initiated. Other objects will be in part obvious or in part pointed out hereinafter.

The invention accordingly consists in the features of construction, combinations of elements, and arrangements of parts, as will be exemplified in the structure to be hereinafter described, and the scope of the application of which will be indicated in the following claims.

One embodiment of the invention has been illustrated in the drawings, in which:

Fig. 1 is a front elevation of the improved cylindrical grinding machine;

Fig. 2 is a hydraulic piping diagram showing the hydraulic actuating mechanisms and control valves and piping therefor;

Fig. 3 is a simplified electric wiring diagram showing the electrical controls for the various mechanisms of the machine;

Fig. 4 is a fragmentary vertical sectional view, on an enlarged scale, through the control valve apron, showing the control levers in elevation;

Fig. 5 is a fragmentary vertical sectional view, on an enlarged scale, taken approximately on the line 5.5 of Fig. 4, through the reversing lever and control apron;

Fig. 6 is a fragmentary vertical sectional view, on an enlarged scale, taken approximately on the line 6-6 of Fig. 4, through the start-stop lever and control apron;

Fig. 7 is a vertical cross sectional view, on a reduced scale, through the wheel slide and wheel Fig. 8 is a fragmentary sectional view, on an enlarged scale, through the hydraulic rapid grinding wheel positioning mechanism showing the shoulder feed control valve;

Fig. 9 is a vertical sectional view, on an enlarged scale, through the manually operable feed wheel;

Fig. 10 is a fragmentary front elevation of the manually operable feed wheel and associated parts, together with the fluid motor for producing the grinding feed;

Fig. 11 is a fragmentary sectional view, on an enlarged scale, through the manually operable table traverse mechanism;

Fig. 12 is a fragmentary hydraulic diagram of the grinding feed mechanism, showing the bypass valve in a by-pass position;

Fig. 13 is a horizontal sectional view, onan enlarged scale, through the feed screw clutch; and

Fig. 14 is a fragmentary detail view of the spring-pressed detent for positioning the clutch actuating lever.

An improved hydraulically operated grinding machine has been illustrated in the drawings comprising a base l8 which serves as a support for a longitudinally reciprocable work table II. The work table II is slidably mounted on a fiat way l2 and a V-way |3 formed on the upper surface of the base ID.

A transversely movable grinding wheel slide I5 is slidably mounted in the usual manner on a pair of transversely extending flat and V-ways (not shown). The wheel slide l5 serves as a support for a rotatable grinding wheel l6 which is mounted on one end of a rotatable wheel spindle I1. The wheel spindle H is preferably driven by means of an electric motor |8 mounted on the upper surface of the wheel slide l5. The motor I8 is provided with a multi V-grooved pulley |9 which is connected by multiple V-belts with a pulley 2| mounted on the other end of the wheel spindle |1.

The slide I5 is arranged to be fed transversely relative to the base ID by means of a feed screw 22 which is journalled in anti-friction bearings 23 and 24. A half nut 25 depending from the under side of the table II meshes with the feed screw 22. It will be readily apparent from the foregoing disclosure that a rotary motion of the feed screw 22 will impart a transverse feeding movement through the nut 25 to the wheel slide I5 to the grinding wheel |6. A manually operable feed wheel 26 is mounted on the front of the machine base to facilitate manual adjustment of the feed screw 22. The driving connections between the hand wheel 26 and the feed screw 22 will be more fully described hereinafter.

The work table II is arranged so that it may be transversed longitudinally by means of a manually operable traverse wheel 21 which is operatively connected in the conventional manner to rotate a gear mechanism which meshes with a rack bar 28 (Fig. 11) depending from the underside of the work table II. The table II is also arranged so that it may be reciprocated longitudinally by an automatically controlled hydraulically operated mechanism comprising a cylinder 29 which is mounted on the underside of the table II. The cylinder 29 contains a pair of spaced pistons 38 and 3|. The pistons 38 and 3| are connected by hollow piston rods 32 and 33 respectively with hollow brackets 34 and 35 which are fixedly mounted on opposite ends of the machine base In.

A fluid pressure system is provided comprising a fluid pump 36 which is driven by an electric motor 31. The fluid pump 36 draws fluid through a pipe 38 from a reservoir 39 formed within the base ID of the machine. The pump 36 forces fluid under pressure through a pipe 40, through a balanced pressure relief valve 4|, and through a pipe 42 to a manually operablestart and stop valve 43. The pipe 42 also conveys fluid under pressure to a combined table reverse and dwell control valve 44 and also conveys fluid under pressure to a table reverse control valve 45. In the position of the valves as shown in Figure 2, a fluid actuated by-pass valve 46 is provided so that fluid may be readily by-passed between opposite ends of the cylinder 29 when the parts are in condition for a manual transversing movement of the table II. As illustrated in Fig. 2, fluid within a cylinder chamber 41 may pass hollow bracket 34, through a pipe 48, through a hollow bracket 35, and through the hollow piston rod 33 into a cylinder chamber 5| formed at the right hand end of the cylinder 29. It will be readily apparent from the foregoing disclosure that in this position of the by-pass valve 46, the table II may be readily traversed by manual rotation of the traverse wheel 21 without the necessity of overcoming an unbalanced fluid under pressure within the system.

The start-stop valve 43 is arranged to be manually operated by means of a start-stop lever 52 which is mounted on the outer end of a rock shaft 53 which is in turn rotatably supported in flxed relation with the base III of the machine. The rock shaft 53 is provided with a downwardly extending arm 54, the lower end of which is yokeshaped and provided with studs 55 which engage a collar 56. The collar 56 rides in a groove 51 formed in the right hand end of a valve stem 58. The valve stem 58 is provided with a plurality of valve pistons formed integral therewith forming valve chambers 59, 60, 6|, 62 and 63.

In addition to serving as a start-stop valve, the valve 43 also serves as a speed control valve to regulate the speed of travel of the table II so that it may be traversed at either a grinding speed or a very slow speed for a grinding wheel truing operation. A needle valve 64 is provided for regulating the grinding speed and a needle valve 65 for regulating the truing speed of the table II. The operation of the start-stop valve 43 and the needle valves 64 and 65 will be more fully described hereinafter.

The combined reverse and .dwell control valve 44 comprises a valve stem 66 which serve as a support for a pair of pilot valves 61 and 68. The central portion of the valve stem 66 located between the pilot valves 61 and 68 serves as a support for a slidably mounted reversing valve 69. The reversing valve 69 i a piston type reversing valve having valve chambers or channels 10 and 1| which function in a manner to be hereinafter described to control the reversal of the table II. A reversing lever 12 is keyed to a rotatable sleeve 13 which is in turn journalled on a cylindrically shaped supporting member 14 (Fig. 5) which is fixedly supported relative to the base Hi. The sleeve 13 is provided with a downwardly extending arm 15 which is connected in the conventional manner by a stud 16 and a shoe 11 which rides in a groove 18 adjustably mounted on the valve stem 66. It will be readily apparent from the foregoing disclosure that when the reversing lever 12 is rocked in either direction,- an endwise motion will be imparted to the valve stem 66.

The downwardly extending arm 15 is also connected by means of a stud 19 and a shoe with a spool shaped member 8| which is adjustably mounted on the left hand end of a valve stem 82 of the reversing control valve 45. The valve stem 82 is provided with a plurality of integrally formed valve pistons forming -valve chambers 83, 84, 85, 86, 81 and 88 which control the passage of fluid'through the valve in a manner to be hereinafter described.

The control lever 12 is arranged so that it may be operated manually to reverse the direction of travel of the table or may be actuated automatically by means of a pair of table dogs 98 and 9| which are adjustably supported by a T slot 92 formed in the front face of the work table II. The positions of the dogs 90 and 9| determine the length of the reciprocatory stroke of the table In order to facilitate a truing operation,

As illustrated in Fig. 5, the manually-operable part, of the control lever 12 is pivotall mounted on a horizontally arranged stud 93 which is supported by a second part 12a of the control lever 12. The manually operable part of the control lever I2 is arranged to rock about the stud 93 as a pivot and the combined control lever 12-120 is arranged to rock with the sleeve I3 to shift the valves 44 and 45. The control lever 12 is'provided with an inwardly projecting stud 04 which is arranged, in the path of the dogs 90 and when it is desired to extend the traverse oi the table II for a truing operation, the control lever I2 isrocked in a counter-clockwise direction (Fig. so as to rock the pin or stud 04 out of the path of the dog 8| so that the table II may traversea further distance toward the left. The movement of the table I I toward the left is determined by a third table dog 95 (Fig. 1). The lever I2 may be rocked either manually or automatically. As illustrated in Fig. 5, a tension spring 88 normally holds the control lever 12 with the stud 04 in an operative position.

The pilot valve 81 is formed with a valve chamber I00 which is operatively connected by a passage with a valve chamber I 02 formed between the pilot valve 81 and the reversing valve 59. the position illustrated in Fig. 2, fluid within the pilot valve chamber I00 may exhaust through a needle valve I04 which serves to control the shift ing movement of the reversing valve 69 toward the left. Similarly, the pilot valve 68 is provided with a valve chamber I0l (Fig. 2) which is connected by a passage with a valve chamber I03 located between the pilot valve 68 and the reversing valve 59. In the position of the pilot valve as shown in Fig. 2. fluid under pressure from the pipe 42 enters the pilot valve chamber IM and passes through the passage into the valve chamber I03 to cause the reversing valve 69 to move toward the left at a speed controlled by the needle valve I04.

A needle valve I05 is similarl connected so that when the valve parts are shifted in the opposite direction, the needle valve I05 will control fluid exhausting from the valve chamber I03 thereby controlling the rate of movement of the reversing valve 88 toward the right. It will be readily apparent from the foregoing disclosure that the needle valves I04 and I05 serve as dwell control valves independently to control the extent of dwell at each end of the table stroke during a traverse grinding operation.

when it is desired to start a traverse grinding operation, the start-stop lever 52 is rocked in a counter-clockwise direction (Fig. 4) so as to shift the valve stem 58 toward the right (Fig. 2). The movement of the valve stem 58 toward the right is limited by movement of a collar I08 which is fixedly mounted on the left hand end of the valve stem 58 into engagement with a surface I 01 of the valve casing 48. When the valve stem 58 is moved to the extreme right hand position, fluid under pressure from the pipe 42 enters a valve chamber 52 and passes outwardly through a pipe I08 which conveys fluid through a pipe I09 into a cylinder chamber IIO to cause a piston III to move toward the left (Fig. 2). This movement of the piston III serves to render the manually oper'able traverse mechanism inoperative during hydraulic movement of the table I I. At the same time fluid under pressure passing through a pipe m passes through a pipe m into a valve enamber I I3 in the by-pass valve 48 to shift the valve piston toward the left (Fig. 2) so asto close the by-pass of fluid between the pipes 48 and shown in Fig. 2, fluid under pressure passes through a pipe 4 to a selector valve II! to be hereinafter described. H a

There is a differential piston area between the pilot valves 51 and '68 and the reversing valve 69. When the valve stem 68 is moved by shifting of the. table reversing lever 12, fluid under pressure is admitted to either the valve chamber I02 or the valve chamber I 03 depending upon thedirection of movement of the reversing lever 12. Admission of .fluid under pressure into valve chamber I02 or I03 serves to shift the reversing valve 69 to cut-oil both intake and exhaust of fluid from'the table cylinder 20. Just before the reversing valve 89 reaches this position, the reverse control valve 45 is shifted so that the tapered portion'of the valve piston I20 decelerates the movement of the table I I. Due to the differential piston areas between .pilot valve's 61-68 and the reversing valve 59, fluid under pressure in either valve chamber I02 or I03 serves to complete the shifting of the reversing valve 69, the reversing lever 12 and the reverse control valve 45 so as togradually accelerate and start the table I I moving in the opposite direction. When the valve move:- into the reverse position, a tapered portion of the valve piston I20 serves gradually to a'cceleratethe movement of the table II as it starts moving in the reverse direction.

In the position of the valve 44 (Fig. 2), fluid under pressure in the pipe 42 passe through the valve chamber II and out through a pipe H6 which connects with the hollow bracket" 34 sons to admit fluid under pressure to the cylinder chamber 41 thereby causing the cylinder 29 andthe table I I to move toward the left. During this movement of the table I I, fluid may exhaust from the cylinder chamber 5| through a pipe II'Iinto the valve chamber I0. Fluid exhausting into the cylinder chamber I0 passes through a pipe 8' into the valve chamber 60 in the valve 43 and 'tions of a valve piston I20 located between the valve chambers 84 and 85; the exhaust of fluid through the pipe H9 may be gradually cut oil to decelerate the motion of the table II before reversal and also gradually to accelerate the table after reversal has taken place. Fluid exhausting through valve chambers 84 and 85 of the valve 45 exhausts through a pipe I2I into the reservoir 39. It will be readily apparent from the foregoing disclosure that the combined reversing and pilot valve 44 serves to control the reversal of fluid under pressure within the hydraulic table cylinder and through throttle valves I04 and I05 independently'controls the duration of dwell at each end of the table stroke. The valve 45 serves precisely to regulate fluid exhausting from the table cylinder through the valve 44 and the valve 43 so as to cause a gradual deceleration of the table movement prior to reversal and a gradual acceleration of table movement after reversal has 7 taken place thereby producing a precise accurate reversal of the table I I.

The needle valve 65 associated with the startstop valve 43 serves to control fluid exhausting from the table cylinder when the valve 43 is in a truing position to produce a slower predetermined movement of the table II during a grinding wheel truing operation. The needle valve 65 is connected into the pipe line I I9.

The table II continues its movement toward the left until table dog 9I engages stud 94 on the reversing lever H and rocks the reversing lever in a counter-clockwise direction to shift the valve stems 66 and 82 toward the right. Movement of the valve stem 66 toward the right serves to cut ofi fluid pressure from the valve chamber 10 but previous to that time the tapered end portion of the valve piston I20 gradually closes the exhaust port in the valve 45 to gradually dece erate the movement of the table I I. At the same time fluid under pressure from the pipe 42 is admitted to the pilot valve chamber I00, and through the passage into the valve chamber I02 to shift the reversing valve 69 toward the right (Fig. 2). During the movement of the reversing valve toward the right, fluid within the valve chamber I03 exhausts through pilot valve chamber WI and needle valve I05. The rate of shifting of the reversing valve 69 is determined by the setting of the needle valve I05 so that the period of dwell at the left hand end of the stroke is readily controlled. After the reversing valve 69 has moved through a predetermined distance toward the right, fluid under pressure in the pipe 42 may enter the valve chamber in the valve 44 and pass outwardly through the pipe II1 into the cylinder chamber 5| to cause the table I I to start its movement toward the right. The starting of the table movement toward the right is controlled in a manner similar to that expressed above. Fluid within the cylinder chamber 41 exhausts through the valve chamber 1I, through the pipe II8, through the valve chamber 60 in the startstop valve 43 and out through the needle valve 64 into the valve chamber 83 of the valve 45 so that the tapered portion of the valve piston I will gradually open the exhaust port to gradually increase the exhaust of fluid through the pipe I2I thereby to gradually accelerate the movement of the table II in a direction toward the right. It will be readily apparent from the foregoing disclosure that the direction of movement of the table I I is determined by the actuation of the reversing valve 44 and the reversal of the table I I is precisely controlled by the simultaneous actuation of the reverse controlling valve 45.

A wheel positioning and feeding mechanism is provided for rapidly causing the grinding wheel I6 to move forwardly to an operative position after which the wheel is advanced at a slow predetermined grinding rate by means of an independent mechanism. The rapid positioning mechanism comprises a slidably mounted sleeve I which supports the anti-friction bearings 23 which in turn support the rear end of the feed screw 22. A piston rod I 26 is fixedly mounted relative to the sleeve I25 in axial alignment with the feed screw 22. The piston rod I26 is connected to a piston I21 which is slidabl mounted within a. hydraulic cylinder I28. The cylinder I28 is fixedly mounted relative to the base I0 of the machine.

A feed control valve I29 is mounted directly below the cylinder I28. This valve is a piston type valve comprising a valve stem I30 having valve pistons I5, I32, I33, I34 and I35 formed integrally therewith. As illustrated in Figure 8, fluid under pressure from the pipe 42 enter a valve chamber I36 located between the valve pistons I3I and I32 and passes through a passage I31 into a cylinder chamber I38 to cause the piston I21 to move toward the right (Fig. 8) into a rearward or inoperative position. During this movement of the piston I21. fluid within a cylinder chamber I39 may exhaust through a passage I40 into a valve chamber MI and out through an exhaust pipe I42.

A compression spring I43 surrounds the valve stem I30 and is interposed between the end cap on the valve I29 and a collar I44 which is fixedly mounted on the valve stem I30. The compression of the spring I43 serves normally to hold the valve stem I30 in its extreme right hand end position (Fig. 8) A solenoid SI serves when energized to shift the valve stem I30 toward the left (Fig. 8) to cause an approaching movement of the piston I21 and the grinding wheel I6.

In the operation of this wheel positioning mechanism, the piston I21 moves forwardly into engagement with the left hand end of the cylinder (Fig. 8) before the wheel I6 engages the surface of the work to be ground. On the normal movement of the wheel I6 and the piston I21 to an inoperative position, the piston moves only part toward the right hand end of the cylinder I28 except when the parts are moved for a grinding wheel truing operation. On the forward rapid stroke of the piston I21, it is desirable to cushion the rapid approaching movement before the piston I21 engages the end of the cylinder I28. This is preferably accomplished by providing a port I45 which is formed at the end of the passage I31 which is spaced from the left hand end of the cylinder I28. It will be readily apparent that when the piston I21 moves a suflicient distance toward the left, the piston I21 will close the port I45 after which fluid may exhaust from the cylinder chamber I38 through a passage I46 through a needle valve I 41 and through a passage I48 into the passage I31, through the valve chamber I36 and out through an exhaust pipe I49. A ball check valve I50 is connected between the passage I 46 and I48 so that on the return stroke of the piston I21 to an inoperative or right hand end position (Fig. 8) substantially unrestricted flow of fluid under pressure from passage I31 through passage I48, through ball check valve I50 into the passage I46 thereby bypassing the needle valve I41 so as to start a rapid movement of the piston I21 toward the right. This movement continues until the port I45 is uncovered by the piston I21 after which fluid under pressure passes through the port I45 to complete the inoperative stroke of the piston I21.

When the wheel I6 is moved to an extreme rearward position, it is desirable to provide an automatic cushioning mechanism to retard the rapid rearward motion as the piston I21 approaches the end of its rearward stroke. A spherical end portion I5I is provided on the right hand end of the piston rod I26 which moves into engagement with a spherical end portion I52 formed on the left hand end of a dash pot piston I53. A dash pot cylinder I54 is provided at the other end of the piston I53 which is'arranged to exhaust fluid through a passage I55, through a needle valve I56, through a passage I 51 which connects with passage I40 so that fluid exhausting from the dash pot cylinder I54 will pass through the control valve I29 and out through the exhaust pipe I42. The setting of the needle valve I56 will determine the rate of rearward movement of the piston I21 as it approaches the end of its stroke thereby reducing the rapid rearward movement to a slow movement thus preventing undue vibrations in the machine. A ball check valve I58 is connected between the passage I51 and the passage I55 so that when fluid under pressure is passed through passage I40 into cylinder chamber I39 to cause an approaching movement of the piston I21, fluid may also pass through a passage I51, the ball check valve I58, the passage I55 into the dash pot cylinder I54 to return the dash pot piston I53 to its forward position so that it is ready for the next cycle of operation. It will be readily apparent from the foregoing disclosure that the grinding wheel I6 may be rapidly moved to and from an operative position by admitting fluid under pressure into either the cylinder chamber I38 or the cylinder chamber I39 which serves to move the grinding wheel rapidly up to the position where it is about to engage the periphery of the work being ground.

A suitable feeding mechanism is provided for producing a slow precise feeding movement of the grinding wheel during the grinding operation. In the preferred form, a hydraulically operated mechanism is provided so that the feed screw 22 may be rotated either continuously for a plungecut grinding operation or intermittently at the ends of the table stroke for a traverse grinding operation. As above described, a manually operable feed wheel 26 is mounted on the front of the machine base I0. The hand wheel 26 is operatively connected to rotate a gear I65 which meshes with a gear I66 which is keyed on the forward end of a rotatable shaft I61. The rear end of the shaft I61 is keyed within the forward end of a rotatable sleeve I68. The forward cylindrical end portion I69 of the feed screw 22 is slidably keyed within the hollow sleeve I68. The forward end of the portion I69 of the feed screw 22 is provided with a spherically shaped stop button I10 which is arranged to move into an engagement with a rounded end of an adjust ably mounted stop screw I carried by the shaft I61. The rapid positioning movement of the grinding wheel I6 and wheel slide I as caused by the piston I21 continues until the stop button I engages the end of the stop screw I1I after which the grinding wheel may be fed at a slow rate either by manual rotation of the feed wheel 26 or by a hydraulically operated mechanism to be hereinafter described.

This hydraulic-mechanism may comprise a cylinder I12 (Fig. 2) which contains a slidably mounted piston I13. A plurality of rack teeth I14 are cut in the upper surface of the piston I13. The rack teeth I14 mesh with a gear I15 which is rotatably supported on a shaft I16. A gear I64 is keyed on the shaft I1 and meshes with the gear I66 so as to transmit motion of the piston I13 to rotate the shaft I61 and the feed screw 22. When fluid under pressure is passed through a pipe I11 into a cylinder chamber I18 to cause the piston I13 to move toward the right (Fig. 2), a counter-clockwise motion is imparted to the hand wheel 26 and also a rotary motion is imparted to the feed screw 22 to cause an infeeding movement of the wheel slide I5. The infeeding movement continues until a stop abutment I8I carried by the feed wheel 26 moves into engagement with a stop pawl I82 which is pivotally supported by a stud I83 on the front of the machine base. During the movement of the piston I13 toward the right, fluid within a cylinder chamber I89 may exhaust through a pipe I90. Similarly, when fluid under pressure is reversed and passed through the pipe I90 into the cylinder chamber I89, the piston I13 will be moved toward the left (Fig. 2) so as to cause a clockwise motion to be transmitted to the hand wheel 26 and also to rotate the feed screw I9 to back off the grinding wheel I6 from the surface being ground.

After a grinding operation has been completed, it is desirable that the piston I13 be moved toward the left Figs. 2, 10 and 12 to start a re-.

setting movement of the feed wheel 26, before the piston I21 starts its rapid rearward movement to an inoperative position. This is preferably accomplished by connecting the exhaust pipe I42 with a normally closed pressure-actuated valve I60. The valve I60 comprises a valve piston I6I which is normally held in a closed position by means of a compression spring I62. When fluid under pressure is admitted to the cylinder I38 to cause a rearward movement of the piston I21, fluid exhausting from the cylinder chamber I39 and the pipe I42 enters a valve chamber formed at the left hand end of the valve I60. The rapid rearward movement of the piston I21 is delayed until sufficient pressure is built up within the valve I 60 to overcome the compression of the spring I62 to move the valve piston I6I toward the right (Fig. 8) so that fluid may exhaust through an exhaust pipe I63 into the reservoir 39. Due to the delayed action of the valve I60, the piston I13 has ample time to start its movement toward the left to cause a rotation of the feed screw 22 to move the grinding wheel I6 out of engagement with the work piece before a rapid rearward movement of the piston I21 is started.

A feed control valve I9I is provided for controlling the admission of fluid to and the exhausting of fluid from the cylinder I 12. The feed control valve I9I is a piston type control valve comprising a valve stem I92 having valve pistons I93, I 94 and I 95 formed integrally therewith. The valve I9I is a fluid pressure operated valve which is arranged so that when fluid under pressure is passed through the pipe 42 into the valve chamber I36 of the feed control valve I29 through the passage I45 into the cylinder chamber I38 to move the piston I21 to a rearward or inoperative position, it will also pass through a pipe I49, through the selector valve H5, and through a pipe I96 into an end chamber I91, and the valve stem I 92 will be moved into an extreme left hand end position as shown in Fig. 2. During movement of the valve stem I92 into this position, fluid within an end chamber I98 may exhaust through a pipe I99. In the position of the valve I9I (Fig. 2) fluid under pressure from the pipe 42 enters a valve chamber located between the valve pistons I94 and I95 and passes out through the pipe I90a to cause the feed piston I13 to move toward the left into the position illustrated in Fig. 2. 'At the same time fiuid Within the cylinder chamber I18 exhausting through the pipe I11 and a pipe I11a enters a valve chamber located between the valve pistons I93 and I94 and passes out through a pipe 200.

It is desirable to provide means for relieving fluid pressure in both ends of the feed cylinder I12 to facilitate manual movement of the feed wheel 26 in case it is desired to move the grinding wheel I6 toward or away from the work, or to facilitate movement of the feed pawl I82 out of the path of the abutment I8I without the necessity of overcoming fluid under pressure within either of the cylinder chambers I18 and I89. This is preferably accomplished by providing a bypass valve 205. The bypass valve 205 is a pressure actuated piston type valve comprising a valve stem 20 6 having a plurality of valve pistons 201, 208 and 209 formed integrally therewith. A compression spring (Fig. 2) contained within the right hand end of the valve 205 serves normally to hold the valve in a feed position (Fig. 2). In this position of the valve 205, pipe I11 is connected thrdugh a valve chamber located between the valve pistons 201 and 208 with the pipe I11a and pipe I90 is connected through a valve chamber located between the valve pistons 208 and 209 with a pipe I90a.

A control valve 2I2 is provided for controlling actuation of the by-pass valve 205. The valve 2 I 2 is a manually operable rotary type valve having a control lever 2I3 which as illustrated in full line position conditions valve 2I2 for a normal grinding operation. When it is desired to actuate the by-pass valve 205, the lever 2 I3 is shifted into dotted line position 2 I3a so that fluid under pressure passing through the pipe 2I6 from the feed control valve I9I passes through a passage 2| 5 in the valve 2I3, through a central aperture in the valve 2| 3 and out through a pipe 2l1 into an end chamber formed at the right hand end of a valve 260. Fluid under pressure passing through the passage 2I5 in the valve 2I2 also passes through a pipe 2 into the valve chamber located between the valve pistons I93 and I94 of the valve I9I and exhausts through a pipe 200. Fluid under pressure entering the end chamber of valve 260 passes through a pipe 2I0 into an end chamber 2 formed at the left hand end of the by-pass valve 205 to shift the valve stem 206 together with the pistons 201 and 208 toward the right into the position illustrated in Fig. 12. In this position,fiuid may readily by-pass from the pipe I11 through the valve chamber located between the pistons 201 and 20B and through the pipe 290 so as to allow free by-pass of fluid between opposite ends of the cylinder I12 thereby allowing unrestrained manual movement of the feed wheel 26.

During a traverse grinding operation, if it is desired to manually control the feed wheel 26 for grinding a portion, such as a shoulder, on the work piece being ground, the lever 2I3 may be shifted in a clockwise direction to shift the valve 2I2 so as to admit fluid under pressure through the pipes 2H and 2I0 to shift the by-pass valve 205 toward the right (Fig. 2) into a by-pass position.

The passage of fluid under pressure through the pipe 2I1 into the cylinder chamber at the right hand end of the cylinder 260 to move the piston 262 toward the left (Fig. 2) so as to maintain the limit switch LSI closed and the work drive motor 261 and the coolant drive motor 266 operative during the manual operation of the feed wheel 26. The start-stop lever 52 may then be shifted to shift the start-stop valve 43 to a stop position which serves to stop the movement of the table II, which also serves to hold the position I21 in its forward operative position. The feed wheel 26 may then be actuated manually to feed the grinding wheel I6 as desired and the table traverse wheel 21 may also be actuated manually to traverse the table II if desired. When it is desired to resume the traverse grinding operation, the start-stop lever 52 may be 12 shifted to shift the start-stop valve 43 to a start position to start the traversing movement of the table II. The lever 2I3 may then be shifted in a clockwise direction to shift the valve 2I2 into the position illustrated in Fig. 2 to cut-off fluid from the pipe 2I0 thereby releasing the compression of the spring to return the by-pass valve 205 to the position illustrated in Fig. 2 so as to resume automatic intermittent feed of the grinding wheel I6 at the ends of the table stroke.

The selector valve II5 above referred to is a rotary type valve having a control lever 2I8 which is arranged to be positioned as shown in full lines in Fig, 2 to facilitate a plunge-cut grinding operation or in a dotted line position 2I8a to facilitate a traverse grinding operation. In the full line position, that is plunge-cut, the selector valve II5 connects fluid under pressure so that the feed control valve I9I is controlled b and in timed relation with the feed control valve I29. When the selector valve II5 is positioned for a traverse grinding operation, that is with the lever in position 2I8a, the control of the feed control valve I9I is shifted so that the start-stop valve 48 will control actuation thereof. In other words, the function of the selector valve II5 is to shift control of the feed control valve I9I from the control valve I29 to the startstop valve 43 and vice versa depending upon whether a plunge-cut or traverse grinding operation is to be performed.

It is desirable to take up any backlash in the grinding feed mechanism rapidly before the grinding wheel engages the peripheral surface of the work to be ground. This is preferably accomplished by a backlash and rapid approach feed control valve 220. The valve 220 is a shuttle type valve comprising a valve stem 22I having valve pistons 222 and 223 formed integrally therewith. The shuttle valve 220 operates in timed relation with the feed control valve I9I. When fluid under pressure is passed through the pipe I96 into the valve chamber I91 to shift the valve stem I 92 toward the left, it also passes through a ball check valve 224 into a valve chamber 225 to move the valve stem 22I toward the left into the position illustrated in Fig. 2. During this movement fluid within a valve chamber 226 may exhaust through the pipe I99, through a chamber in the selector valve II5 and exhaust in the same manner as fluid exhaustin from the end chamber I98 of the valve I9I.

When an infeeding movement is initiated either during a plunge-cut or a traverse grinding operation, both of the valves I9I- and 220 are moved toward the right by fluid under pressure. As illustrated in Fig. 2. the selector valve II 5 is set for a plunge-cut grinding operation. When the solenoid SI is energized to shift the control valve I29 to initiate a rapid approaching movement of the grinding wheel I6, fluid passing through the pipe 42 enters the valve chamber HI and passes through the passage I to initiate a rapid approaching movement of the grinding wheel and also passes through the pipe 221, through a chamber in the selector valve II5 and through the pipe 228 and the pipe I99 into the end chamber I 98 of the valve I9I and also into the end chamber 226 of the backlash control valve 220 to move both of the valves I9I and 220 toward the right (Fig. 2). The valve stem I 92 of the valve I9I moves rapidly into a right hand end position so that fluid under 'pressure in the pipe 42 will pass through the valve chamber located between the valve pistons I93 and I94 of the valve I9I and pass out through the pipe II'Ia-I'I'I into the cylinder chamber I'I9 to initiate a grinding feed. At the same time fluid entering the end chamber 226 of the backlash control valve 229 moves the valve stem 22I toward the right at a rate controlled by a needle valve 229.

During the movement of the valve stem I92 toward the right, a port is uncovered so that fluid may exhaust from the cylinder chamber I99 through the pipe I99 into the valve chamber located between the valve pistons I94 and I95 and passgut through a pipe 239, through a chamber in the selector valve H and pass out through a pipe 23I and exhaust through a plunge-cut feed adjusting valve 232 and a pipe 235 into the reservoir 39. In order to take up backlash in the feed mechanism, fluid exhausting from the valve chamber located between the valve pistons I93 and I94 into the pipe 239 may also exhaust through a chamber located between the valve pistons 222 and 223 of the backlash control valve 229 during movement of the valve stem 22I toward the right and exhaust throughv a needle valve 233 and a pipe 234 into the reservoir 39. The quantity of fluid permitted to exhaust through the backlash control valve is determined by the speed of movement of the valve stem 22I and also the setting of the needle valve 233. By adjustment of the needle valves 229 and 233, suflicient additional fluid may be exhausted from the cylinder chamber I99 of the feed control cylinder I'I2 during its initial movement rapidly to take up backlash in the parts of the feeding mechanism previously described. After the valve stem 22I has moved a sufficient distance so that the chamber located between the valve pistons 222 and 223 moves past the port at the end of the pipe 239, all fluid exhausting from the cylinder chamber I99 must then pass through the selector valve II5, through the pipe 23I and through the plunge-cut feed adjusting valve 232 which controls the rate of plunge-cut infeeding movement of the grinding wheel. The return stroke of the backlash valve stem 22I from its right hand end to its left hand end position is merely a resetting stroke to position the valve for the start of the next grinding operation. During this return stroke when fluid under pressure is passed through the pipe I96, it may pass substantially unrestricted through the ball check valve 224 into'the valve chamber 225 rapidly to move the backlash valve stem 22I into its left hand end position.

When the solenoid SI is deenergized and spring I43 shifts the valve I29 (Figs. 2 and 8) to cause a rapid rearward movement of the grinding wheel I6, fluid may exhaust from the valve chamber I96 of the feed valve I9 I, from the valve chamber 226 of the backlash valve 229 and from the chamber 263 of the valve 269 through the pipe I9I, the pipe 228. through the selector valve II5 through the pipe 221, through a valve chamber located between the valve pistons I32 and I33 of the feed control valve I29, through a central aperture in the valve stem I39, through a valve chamber formed between the valve pistons I34 and I35 and out through an exhaust pipe 236 into the reservoir 39.

A picker feed control valve 249 is provided to control the infeeding movement of the grinding wheel I6 at the ends of the table stroke when the selector valve lever 2 I9 is moved into position 2I9a for a traverse grinding operation. The valve 249 is a shuttle type valve comprising a 14 valve stem 2 having valve pistons 242 and 249 formed integrally therewith. A pipe 244 is arranged to convey fluid under pressure from the pipe 42 through the valve chamber 91 in the reverse control valve 44 into an end chamber 245 in the picker feed control valve 249 to move the valve stem 2 toward the right (Fig. 2). During this movement fluid within an end chamber 246 exhausts through a pipe 241 through a needle valve 249 and a pipe 249 into the valve chamber 99 in the reverse control valve 45 and out through an exhaust pipe 259 into the reservoir 39. The rate of movement of the valve stem 23I may be iz'igulated by the adjustment of the needle valve 9. With the selector valve 6 set in a trayerse grinding position, fluid exhausting from the cylinder chamber I99 passes through the feed control valve I9I in a manner above described through the pipe 239, through the chamber in the selector valve I I6 and through a pipe I and through a traverse infeed adjusting valve 292. through a pipe 253. During the shifting movement of the reversing valve. 44 and the reverse control valve 45, fluid under pressure is admitted to shift the valve stem 2 endwise. During this movement in either direction as controlled by the needle valve 249, a valve chamber 264 momentarily uncovers a port at the end of the pipe 253 to allow a predetermined quantity of fluid to exhaust from the cylinder chamber I99 through the pipe 253, through the valve chamber 254 in the picker feed control valve 249 and out through the exhaust pipe 234. By regulating the picker feed adjusting valve 262 and by regulating the needle valve 249 to control the speed of movement of the valve stem I, a predetermined infeeding movement of the grinding wheel I6 may be obtained during each reversal of the table at the ends of its stroke.

It is desirable to provide means for automati cally stopping and starting the work drive motor and the coolant drive motor so that when the grinding cycle is initiated both of the motors will be set in motion before the grinding wheel is fed into the work. To accomplish this result, a shuttle type valve 269 is provided which contains a pair of disconnected slidably mounted pistons 26I and 262. A chamber 263 is formed between the pistons 26I and 262 so that when fluid under pressure is passed through the pipe I99 it will enter the chamber 263. A slidably mounted plunger *2 engages the left hand end of the piston 26I and is normally urged in a direction toward the right (Fig. 3) by means of a compression spring 265. The plunger 264 is arranged in the path of an actuating roller of a limit switch LSI. When fluid under pressure is admitted to the cylinder chamber 263, the piston 262 being in engagement with the right hand end of the valve 269, the piston 26I will be moved toward the left to transmit a corresponding mo- I will be moved toward the left against the compression of the spring 265 so as to close the normally open limit switch LSI. When the limit switch LSI is closed, a relay CRI is energized so as to energize a relay MC and thereby close a circuit to start the coolant motor 266 and also 15 to energize a relay MH to close a second circuit to start the work drive motor 261 (Fig. 4).

A suitable work supporting and rotating mechanism is provided for rotatably supporting a work piece to be ground during a grinding operation. This mechanism may comprise a headstock 210 which is supported on the work table II. The headstock 210 is provided with a headstock center 21I. A footstock 212 having a footstock center 213 is adjustably mounted adjacent to the other end of the table II. The headstock 210 is preferabiy driven by the electric motor 261 which is mounted on the upper surface of the headstock 210. The motor 281 is provided with a multiple V-groove pulley 214 which is connected by multiple V-belts 215 with a multiple V-groove pulley 216 which is mounted on the left hand end of a headstock spindle 211. Rotation of the motor 281 will be transmitted to rotate the headstock spindle 211 and the headstock center 21! to rotate a work piece to be ground in the conventional manner.

In grinding certain types of work pieces it is frequently desirable to provide a shoulder grinding feed so that in a plunge-cut grinding operation the wheel may be fed at a shoulder grinding feed to grind a shoulder on the work piece after which the feed is slowed down to a predetermined plunge-cut feed to grind a body or cylindrical portion on the work piece. As illustrated in Figs. 2 and 8, a shoulder grinding feed control valve 280 is fixedly mounted relative to the cylinder I28. The valve 280 is a piston type valve comprising a hollow sleeve type valve member 28I. The valve member 28I is provided with a pair of spaced valve pistons 282 and 283 which form a valve chamber 284 therebetaveen. A compression spring 288 within a valve casing 285 normally serves to hold the valve member 28I in a right hand end position (Fig. 8). A rod 281 is fastened to a bracket 288 which is in turn fixedly mounted on the sleeve I25. The rod 281 is provided with a threaded portion having a nut 289 adjustably mounted thereon. When the sleeve I25 is moved toward the left to cause an approaching movement of the grinding wheel I6, the rapid approaching movement continues until the nut 289 engages the end of the valve member 28I and starts it moving in a direction toward the left (Fig. 8). of the rod 281 is supported in a bearing bracket 290. An adjustably mounted dog 29I carried on the right hand end of the rod 281 is arranged in the path of an actuating roller 292 of a limit switch LS2. The limit switch is preferably a normally open limit switch and serves when closed to energize a solenoid valve to be hereinafter described.

In the position of the parts (Fig, 8) when the solenoid SI is energized to shift the valve stem I30 toward the left to initiate a rapid approaching movement of the grinding wheel I6, fluid within the cylinder chamber I38 exhausts through the passage I31, through the valve chamber I36, and out through a port 293, through a pipe 294 into the valve chamber 284 and out through an exhaust pipe 295 into the reservoir 39. The rapid approaching movement of the grinding wheel I6 continues until the nut 289 engages the end of the valve member 28! and moves it toward the left (Fig. 8) so as to cut oil th exhaust pipe 295. In this position of the valve 28I, fluid exhausting into the valve chamber 284 passes out through a pipe 298 and through a shoulder grinding feed adjusting valve 291 and a pipe 298 into the reser- The right hand end voir 39. By adjusting the valve 291, the rate of the shoulder grinding feed may be varied as desired. The shoulder grinding feed is normally more rapid than the cushioning feed at the end of the stroke of the piston I21 as controlled by needle valve I41 so that the shoulder grinding feed will continue until the spherical button I10 of the feed screw shaft I69 moves into engagement with the stop screw I1I after which the body feed of the grinding wheel I6 continues at a rate controlled by the movement of the piston I13 previously described.

During the shoulder grinding feed. it is desirable to retard movement of the feed piston I38 for a plunge-cut grinding operation until the shoulder grinding feed has completed its movement. This is preferably accomplished by means of a normally closed solenoid valve 300. The valve 300 is a piston type valve comprising a valve stem 30I having valve pistons 302 and 303 formed integrally therewith. A tension spring 304 serves normally to hold the valve stem 30I in the position illustrated in Fig. 2. The valve 300 is connected in the pipe line 23I between the selector valve H5 and the plunge-cut feed ad justing valve 232. A valve 305 is positioned in the pipe line 23I to permit preventing any exhaust of fluid through the pipe 23I when a shoulder grinding feed is being employed. With the valve 305 closed, no fluid can exhaust through the pipe 23I from the feed cylinder I13 until the shoulder grinding feed above described has been completed. As the shoulder grinding feed reaches the end of its stroke, dog 29I moving toward the left (Fig. 8) engages roller 292 to close the limit switch LS2 which serves to energize a solenoid S2 to shift the valve stem 30I toward the left (Fig. 2) thus opening the valve 300 so that fluid exhausting from the selector valve II5 may pass through the pipe 23I, through a valve chamber located between the valve pistons 302 and 303 of the valve 300 and out through the plunge-cut feed adjusting valve 232 into the reservoir 39 thus starting the plunge-cut feed of the grinding wheel I 6 to grind the cylindrical body portion of the work piece. The plunge-cut grinding feed contlnues as above described until the abutment I8I carried by the feed wheel 26 engages the end of the stop pawl I82 which serves to stop the infeeding movement of the grinding wheel when the body portion of the work piece has been ground to a predetermined size.

In case it is desired to render the shoulder grinding feed inoperative to obtain a direct plunge-cut grinding feed, the nut 289 is backedoff, that is moved toward the right (Fig. 8) so that it will not engage the valve sleeve 28I during the rapid approaching movement of the piston I21 and the grinding wheel I8. The valve 305 (Fig. 2) is opened to allow fiuid exhausting from the selector valve II5 to by-pass around the solenoid valve 300, thus rendering the solenoid valve 300 ineffective. In this position of the parts, a plunge-cut grinding operation, with shoulder grinding feed, may be obtained. The grinding wheel l6 rapidly approaches the work piece to be ground by movement of the piston I21 toward the left (Fig. 8). The rapid approaching move ment continues until the spherical button engages the stop screw I1I which stop the axial or endwise movement of the feed screw 22 just before the grinding wheel I6 engages the work piece to be ground. The movement of the piston I13 toward the right (Fig. 2), as above described, causes a rotation of the feed screw 22 as v- 17 erned by the plunge-cut adjusting valve 232 to produce the desired plunge-cut feeding movement of the wheel slide and the grinding wheel 16.

The electrical control mechanism is illustrated in Fig. 3. A push button switch 310 is provided to energize a relay 311 to start the wheel drive motor 16. A stop switch 312 is provided so that the motor 18 may be stopped when desired. A push button switch 314 is provided for energizing a relay MP to start the motor 31 for driving the hydraulic pressure pump 36. A stop switch 315 is provided to facilitate stopping the hydraulic motor 31 when desired.

A manually operable wheel feed control lever 316 is pivotally supported by a stud 311 on the front of the machine base. The lever 316 is arranged to acuate either a start switch 316 or a stop switch 319 depending upon the direction of movement of the lever 316. A selector switch 326 is provided so that the feed mechanism may be controlled either manually or automatically in case a semi-automatic operation of the machine is desired.

As illustrated in Fig. 3 the selector switch 326 is illustrated in a manually operable position. When it is desired to shift to a semi-automatic control, the actuating knob of the switch 320 is shifted in a counter-clockwise direction which serves to render an electric timer 321 operative. In this position of the parts, when the control lever 316 is rocked in a counter-clockwise direction (Fig. 3), the switch 318 is closed to set the timer 321 in motion. At the same time the solenoid S1 is energized to shift the feed control valve 129 toward the left (Fig. 8) to initiate a rapid approaching movement of the grinding, wheel 16. The rapid approaching movement of the wheel continues until the spherical button 316 on the feed screw shaft 169 engages stop screw 111 after which the fluid cylinder 112 and piston 113 serve to produce a plunge-cut feeding movement of the grinding wheel 16 to grind a cylindrical portion on the work piece to a predetermined size. After a predetermined time interval, the electric timer 321 breaks a circuit to deenergize solenoid SI thus releasing the compression of spring 143 so that the feed control valve 129 returns to the position illustrated in Fig. 8 to initiate a rapid movement of the piston 121 noid S1 to return the grinding wheel 16 to an inoperative position.

A manually operable control lever 325 is provided for controlling the work driving motor 261. The lever 325 is pivotally supported by the stud 326 on the front of the machine base. The lever 325 is arranged to actuate a start switch 321 or a stop switch 328 is provided so that the work rotation may be either controlled manually or automatically as desired. As illustrated in Fig. 3, the selector switch 329 is shown in a hand position. In this position of the selector switch 329, when control lever 325 is rocked in a counterclockwise direction to actuate the start switch 321 closing a circuit to energize the relay switch MH which in turn serves to close a circuit to start the work drive motor 261. When it is desired to stop the work drive motor 261, the work 18 control lever 325 may be rocked in a clockwise direction to actuate the stop switch 328 thereby breaking the circuit to deenergize the relay switch MH and thereby stopping the motor 261.

If it is desired to operate the work drive motor automatically in timed relation with other mechanisms of the machine, the selector switch 329 is shifted to an automatic position. In this position of the selector switch 329, when the pistons 261 or 262 (Fig. 2) are moved to the left to close the limit switch LS1 so as to close a circuit energizing a relay switch CR1 which in turn serves to energize a relay switch MC to close a circuit to start the coolant drive motor 266 and also to energize the relay switch MI-I automatically to start the work drive motor 261. Similarly, when fluid under pressure is cut off from the cylinder 260, the released compression of the spring 265 serves to move the pistons 261 and 262 toward the right (Fig. 2) to allow the normally open limit switch LS1 to open, thereby breaking the circuit to deenergize the relay switch CR1 which in turn serves to deenergize the relay switch MC to stop the coolant drive motor 266 and also to deenergize the relay switch MH to break a circuit and thereby stop the work drive motor 261.

If it is desired to jog the work, that is to turn the work through a partial turn in setting up the machine or for purposes of inspection of the work piece being ground, the control lever 325 may be rocked in a clockwise direction so that the switch 326 momentarily closes contacts 330 which serves to energize relay switch MH to close a circuit thereby starting the work drive motor 261. The extent of the jogging motion of the motor 261 depends upon how long the control lever 326 holds the switch to close contacts 336.

To facilitate setting up the feeding mechanism of the machine when a new wheel is mounted thereon or to set up for a different diameter work piece, it is desirable to provide means for disconnecting the feed wheel 26 from the power actuated mechanism. This is preferably accomplished by means of a clutch mechanism whereby the fluid motor may be disconnected from the feed wheel 26 and feed screw 22. This mechanism comprises a manually operable lever 345 which is rotatably supported in back of the feed wheel 26. The lever 345 is provided with a downwardly extending arm 346 having a cylindrical arrow pointed end portion 341 which is arranged to engage a spring-pressed detent 348 which serves to hold the lever 345 in either a clutched or declutched position. A pivotally mounted bell crank lever 349 is supported by a vertical stud 359. The stud 356 is carried by a bracket 351 mounted on the front of the machine base 16. The bell crank lever 349 is provided with a yoked portion having a pair of opposed screws 352 and 353 which are arranged to engage diametrically opposite sides of the cylindrical arrow pointed projection 341 of the arm 346. The bell crank lever 349 is also provided with a second yoked portion 354 which carries diametrically arranged studs 355 and 356. The studs 355 and 356 are arranged to engage a groove 351 formed in an enlarged sleeve 358 which is fixedly mounted on the forward end of the shaft 116. A clutch member 359 is keyed to the inner end of the shaft 116 (Fig. 13). The clutch member 359 comprises an internal gear which is arranged to mesh with an external gear of the same pitch diameter which is fixedly mounted relative to the gear 115. In the position shown in Fig. 15, the clutch mem- 19 bers 359 and 360 are engaged so that movement of the piston 113 will be transmitted through the rack 114, the gear 115, the clutch parts 360-359, the shaft 116, the gear 164 to rotate the gear 166 which transmits a rotary feeding movement to the feed screw 22 'and also to the feed wheel 26. If it is desired to declutch the piston 113 from the feed screw 22 and the feed wheel 26, the clutch lever 345 is rocked in a clockwise direction (Fig. to rock the bell crank lever in a counter-clockwise direction so as to move the shaft 116 toward the right (Fig. 13) so as to disengage the clutch member 359 from the clutch member 360. In this position of the clutch parts, the feed wheel 26 may be manually rotated to rotate the feed screw and rapidly to position the grinding wheel as desired.

A micrometer adjustin device 385 is provided to facilitate adjustment of the stop abutment 181. A gear 386 is formed integral with the gear 165. A pinion 381, formed integral with the rotatable shaft 388, meshes with the gear 386. A star wheel or gear 389 is keyed to the shaft 388. A springpressed detent 390, carried by the hand wheel 26, meshes ,with or engages the gear 389. A collar 391 is fixedly mounted on the gear 389 and is provided with an annular integral flange 392 which in the position illustrated in Fig. 9 engages a notch 393 formed in the detent 390 to lock the detent 390 in engagement with the star wheel or gear 389 thereby preventing rotation of the pinion 381. A compression spring 394 normally serves to hold the detent 390 in a locked position. A manually operable knob 395 is fixedly keyed on the outer end of the shaft 388. If a rapid adjustment of the stop abutment 181 is desired, in setting-up the machine, the knob 395 (Fig. 9) may be pulled toward the left to move the pinion 381 out of mesh with the gear 386 after which the hand wheel 26 may be rotated to the desired position. When it is desired to adjust the posi tion of the stop abutment 181 relative to the gear 386, the knob 395 is moved toward the right (Fig. 9) against the compression of the spring 394, to unlock the detent 398 and the knob 395 is then rotated to rotate the pinion 381 on the stationary gear 386 thereby readjusting the position of the abutment 181. When the knob 395 is rotated, the teeth of the star wheel or gear 389 ride over the spring-pressed detent 390. star wheel 389 resets the abutment 181 relative to the gear 381 by an amount required to allow an advance of one ten-thousandth of an inch (.0001")- of the grinding wheel 16. It will be readily apparent that by a rotary adjustment of the knob 395, the stop abutment 181 may be precisely adjusted to facilitate setting up the machine for grinding work pieces to a predetermined size. This adjustment may also be utilized for resetting the stop abutment 181 to compensate for wheel wear and for resetting after a grinding wheel truing operation.

A manually operable table traverse mechanism is illustrated in Fig. 11. The manually operable traverse wheel 21 is keyed on the outer end of a rotatable shaft 310. A gear 311 is formed integral with the shaft 318 and meshes with a gear 312. The gear 312 is keyed to a rotatable shaft 313. The shaft 313 also supports a gear 314 which is arranged to mesh with a gear 315. The gear 315 is slidably keyed on a rotatable shaft 316. A gear 311 is also keyed on the shaft 316 and meshes with the table rack bar 28. A yoked member 318 is fixedly mounted on a. slide rod 319. The yoked member 318 is arranged to engage a Each notch on the groove 381) formed integral with the gear 315 so that an endwise or axial movement of the rod 319 will throw the gear 315 into or out of mesh with the gear 311. A compression spring 381 serves normally to urge the rod toward the right to maintain the gear 315 in mesh with the gear 311 so that a manual rotation of the hand traverse wheel 21 will be imparted through the gear mechanism above described to cause a longitudinal traversing movement of the table 11. As previously described, when a fluid pressure reciprocation of the table 11 is started, fluid under pressure passes through the pipe 1119 into the cylinder chamber to move the piston 111, the rod 319, the yoked member 318 toward the left (Fig. 11) to slide the gear 315 toward the left to throw it out of mesh with the gear 311 so as to rend :r the manually operable traverse wheel 21 inoperative durin hydraulic reciprocation of the table 11.

In order to facilitate bleeding the hydraulic system, a manually operable bleeder valve 335 is connected by a pipe 336 with left hand end of the cylinder 29 (Fig. 2). A pipe 331 conveys fluid exhausting through the valve 335 to the reservoir 39. Similarly a manually operable bleeder valve 338 is connected by a pipe 339 with the right hand end of the cylinder 29. exhausting through the valve 338 to the reservoir 39. The bleeder valves 335 and 338 may be manually opened when desired.

The operation of the improved grinding machine will be readily apparent from the foregoing disclosure. Assuming the mechanisms to have been previously adjusted and the selector valve is positioned with lever 218 in a plunge-cut grinding position as illustrated in Fig. 2, the selector switch 239 positioned for manual control and the selector switch 220 positioned for a manual control (Fig. 3), the machine is started. Push button switch 310 is actuated to start the wheel driving motor 18. The start switch 314 is actuated to start the hydraulic pump motor 31 and the coolant pump motor 266. The work control lever 325 is then rocked in a counter-clockwise direction to actuate the start switch 321 to energize relay MH and thereby start the work drive motor 261. A feeding movement of the'grinding wheel 16 may then be obtained by rocking the wheel feed control lever 316 in a counter-clockwise direction to actuate the infeed switch 318 which serves to energize the solenoid S1, as above described, to shift the feed control valve 129 into an infeeding position to cause a rapid approaching feed of the piston 121 which continues until the spherical stop button 110 on the feed screw engages the stop screw 111 after which a slow plunge-cut feed of the wheel is obtained by movement of the piston 113 toward the right (Fig. 2) which transmits a rotary motion to the feed screw. The grinding feed continues until stop abutment 181 carried by the feed wheel 26 engages the stop pawl 182 which stops the infeeding movement of the grinding wheel 16. The wheel feed control lever 316 may then be rocked in a clockwise direction to actuate the stop switch 319 which deenergizes the solenoid S1 thereby releasing the compression of the spring 143 to return the feed control valve 129 into the position illustrated in Fig. 8 to cause the grinding wheel to move to a rearward or inoperative position. When the valve 129 moves to this position, the piston 113 moves toward the left to rotate the feed screw 22 thereby resetting the feed wheel 26 and associated parts into their original position. Due

A pipe 340 conveys fluid- 

